(3+4x)*2x=65

Solution for (3+4x)*2x=65 equation:

(3+4x)*2x=65

We move all terms to the left:

(3+4x)*2x-(65)=0

We add all the numbers together, and all the variables

(4x+3)*2x-65=0

We multiply parentheses

8x^2+6x-65=0

a = 8; b = 6; c = -65;
Δ = b2-4ac
Δ = 62-4·8·(-65)
Δ = 2116
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2116}=46$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-46}{2*8}=\frac{-52}{16}
=-3+1/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+46}{2*8}=\frac{40}{16}
=2+1/2
$